Minimizing the Pain in Air Transportation: Analysis of Performance and Equity in Ground Delay Programs




Manley, Bengi

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The air transportation system is a significant "engine" of the U.S. economy providing rapid, safe, secure, affordable transportation over large geographic distances. Growth in passenger and cargo transportation demand (i.e. flights) in excess of the growth in air transportation capacity (i.e. runways, airspace sectors) has resulted in massive systemic delays. These delays are estimated in 2007 to have cost passengers up to $12 billion, and to have cost the airlines $19 billion in excess direct operating costs. With the current trend in rising fuel prices, the economic impact of these delays is expected to strain the U.S. economy even more. These delays also contribute to local air and water quality issues and to global climate change. Systematic solutions to address the imbalance between scheduled demand and forecast capacity include: (1) increasing capacity through the construction of new airports and additional runways at existing airports, (2) better utilization of existing capacity by increasing throughput productivity through advanced satellite-based navigation and 4-D trajectory planning, (3) demand management through administrative measures (such as the High Density Rule) and market-based mechanisms (such as congestion pricing and auctions of airport and airspace slots). Solutions 1 and 2 are capital intensive and require decades of planning and development. Solution 3 can be implemented rapidly but faces strong political opposition. In the absence of scheduling flights within the constraints of the capacity, flights arriving at an airport in excess of the airport arrival capacity are delayed until an arrival slot is available. Traditionally, flights that needed to be delayed were required to fly "holding patterns" above the airport until an arrival slot became available. To avoid these foreseen airborne holding delays, and to increase safety, the U.S. Air Traffic Control system runs a Ground Delay Program (GDP). The GDP holds the flights on the ground at their origin airports, allowing them to depart only when arrival slots will be available at the time the °ight is estimated to arrive at the constrained destination airport. Although the GDP was originally designed to manage reductions in capacity due to weather, over the last decade the GDP is routinely used to manage systemically over-scheduled arrivals. The GDP rations the available airport arrival capacity based on scheduled arrival times of flights (i.e. first-scheduled, first served). Special care is taken to equitably distribute delays between airlines. The Ration-by-Schedule approach is "airline flight-centric" and does not explicitly take into account passenger trip delays, fuel flow effciency, and emissions. Previous research evaluated alternate rationing rules using airline-flight centric metrics. The objective of this research is to examine the impact of alternative GDP rationing rules on the performance and equity to airlines and passengers. The hypothesis is that alternate GDP rationing rules can maximize the mutual interests of both airlines and passengers. This dissertation describes the GDP Rationing Rule Simulator (GDP-RRS) that was developed to evaluate alternate rationing rules. The dissertation also describes the results of three experiments conducted for flights affected by GDPs in 2007 for arrivals at the three New York Metroplex airports (Newark Liberty (EWR), LaGuardia (LGA) and John F. Kennedy (JFK) airports). The first experiment compared the performance and equity of five alternate rationing rules to the Ration-by-Schedule rationing rule. The second experiment evaluated the impact of substitution strategies in the GDP rationing rules. The third experiment investigated the impact of GDP scope on performance and equity for airlines and passengers. The major findings of the research are: * It is not possible to maximize the mutual interests of airlines and passengers. There exists a tradeoff between GDP performance and equity (see below). * When only performance is considered (and equity for both airlines and passengers are ignored), the best rationing rule is Ration-by-Passengers. This rule maximizes passenger throughput. Passengers experience a reduction in passenger delays of 23% at EWR, 20% at LGA, 15% at JFK relative to the Ration-by-Schedule rule. Airlines experience savings of 57% fuel burn at EWR, 63% at LGA, 42% at JFK relative to the Ration-by-Schedule rule. * When only equity due to flight and passenger delays are considered (and performance of both airlines and passengers are ignored), the rule that provides the best equity is Ration-by-Schedule. * When performance and equity of flight delays for airlines are considered (and performance and equity for passengers are ignored), the rules that provide the best performance differs by airport: Ration-by-Passengers at EWR, Ration-by-Aircraft Size at LGA, and Ration-by-Distance at JFK. * When performance and equity for passengers are considered (and performance and equity for airlines are ignored), the rules that provide the best performance differ by airport: Ration-by-Distance at EWR and LGA and Ration-by-Passengers or Ration- by-Fuel Flow High Precedence at JFK. * When performance and equity for both airlines and passengers are considered, the rules that provide the best performance and equity differs by airport: Ration-by- Distance at EWR, Ration-by-Aircraft Size at LGA, and Ration-by-Passengers at JFK. * Airline equity is determined by the flight schedule (i.e. position of flights throughout the day) and the aircraft type (i.e. fleet mix). * Passenger equity is determined by the flight cancellations. * Airlines with a small number of operations and airports with a small number of enplanements, experience disproportional performance and equity penalties. * Airline substitution strategies do not change the relative performance and equity of the alternate rationing rules. * Changes in GDP scopes do not change the relative performance and equity of the alternate rationing rules. Scope is the distance range of the GDP. * The selection of the GDP rationing rule requires the unambiguous definition of the National Air Transportation System objectives (and the weights for the performance and equity). The relative weighting of objectives is a social and political activity. The application of alternate GDP rationing rules has broader implications. GDP rationing rules create priority queues which give preference to the compliant flights. As a consequence the rationing rules incentivize airline behavior related to scheduling and fleet mix. For example, the Ration-by-Passengers rule could, in the long-run, result in the migration of airline fleets to larger sized aircraft that would increase the passenger flow capacity. This would improve the efficiency of the air transportation system. This incentive would result in an increase in aircraft size, which would lead to reduced frequency, which would yield lower delays.



Performance, Equity, Ground Delay Program, Passenger Delay, Fuel Burn, Delay